The present disclosure relates to an electromotive adjustment device for a piece of furniture, the piece of furniture including one or more adjustable furniture parts. The electromotive adjustment device includes a housing, at least one drive gear motor, a control device and a drive unit, the output member of which is connected to a furniture component of the piece of furniture to be adjusted or to an input member of an adjustment fitting. A safety device is provided by which the drive gear motor can be brought to a standstill and/or reversed during pinching between operatively connected furniture parts or between a furniture part and another component or between a furniture part and a part of a body.
An electromotive adjustment device is known in many embodiments. A specific embodiment depends on the type of the furniture to be adjusted, for example, a slatted base, a hospital or nursing bed, or seat and reclining furniture, or the height adjustment of a table board.
Since the adjusting speeds of the furniture parts to be adjusted are relatively low, the gear of the drive gear motor is a speed-reduction gear, for example, in the form of a worm drive. The drive motor of the gear motor is a DC motor to be driven with a safe DC voltage. The drive unit to be driven by the gear motor may be a spindle drive, for example, wherein either the spindle is rotatably driveable and a spindle nut, which is placed thereon and which is secured against rotation and will be displaced in the longitudinal direction of the spindle when the drive gear motor is activated, or conversely the spindle is secured against rotation and will displace in the longitudinal direction, and the spindle nut will be rotated. The output member of the drive unit is rigidly connected with the linearly movable gear component. This can be a lifting tube, for example, which comprises a fork head at the free end, which is connected in an articulated manner to the furniture part to be adjusted or to the input member of an adjustable fitting.
Such adjustment devices are known as single or double drives. In the case of single drives, a drive unit is coupled with the drive gear motor, whereas in the case of a double drive drive units are provided which are coupled with a gear motor or with two gear motors and which are arranged in a common housing.
Other adjustment devices are known as so-called lifting columns and are in connection with a component of a height-adjustable table, a height-adjustable worktop or a height-adjustable bed. The lifting columns are arranged in the manner of a single drive, wherein the lifting columns comprise at least one spindle drive and at least one extensible lifting tube. They are arranged in each other in the manner of guide tubes in the case of an arrangement with several lifting tubes, and are mounted on each other with guide means and are guided among each other.
The safety device is known in the field as a pinch protector. It is intended to prevent body parts of persons or pets from being inadvertently pinched, which might lead to injuries. Since the adjustment devices for furniture are mass products, they should be producible at exceptionally low cost.
In the case of known safety devices, switching strips are used which are relatively expensive. Furthermore, such switching strips are disturbing. Safety devices are also installed in the drive unit or in the drive gear motor for the reasons as mentioned above. It is disadvantageous, however, that adjustment devices that are already in operation cannot be retrofitted.
The present disclosure provides for an electromotive adjustment device configured in such a way that the safety device can be arranged in a simple manner and can be produced at low cost. Such a safety device is arranged in such a way that electromotive adjustment devices which are already in operation can be retrofitted with the safety device according to embodiments of the present disclosure.
An embodiment of the present disclosure relates to a safety device comprising a light transmitter configured such that the generated light beam is directed against at least one furniture part to be adjusted or a further component which is in connection with this furniture part. The light beam impinging on the furniture part or the further component in connection with this furniture part will be reflected and will meet a light receiver. Electrical signals can, in accordance with the present disclosure, be generated in the case of a change in intensity of the reflected light caused by a deformation of the furniture part by a signal converter, so that after evaluation of the signals by control electronics of the control unit the drive gear motor can be shut down and/or reversed.
Thus, the safety device may, according to the present disclosure, be arranged as an optical system, so that by using a light transmitter and a light receiver the system will be very inexpensive, and that existing electromotive adjustment devices can also be retrofitted with this system. This optical system detects the deformation of a furniture part, for example, a table board, in a contactless manner. In this process, even the relatively low deformations occurring during pinching will be detected, so that this system can be regarded as a direct connection. Furthermore, this contactless and optical detection is independent of the material used.
It is advantageous, in accordance with the present disclosure, if the light transmitter and the light receiver are arranged in a housing which is coupled with the furniture part to be adjusted. It is advantageous, in accordance with the present disclosure, if the light transmitter and the light receiver are installed in the housing of the control unit, since this very much simplifies the retrofitting capability of existing electromotive adjustment devices.
Appropriately, in accordance with the present disclosure, the mutually facing areas of the housing and the furniture part are spaced from one another at a relatively low distance. This distance can be in the range of 1 mm, for example, so that even exceptionally slight deformations of the furniture part in the case of pinching, will be registered and can be evaluated. This distance can, for example, also be changed by a respective adjustment feature. If the light transmitter and the light receiver are arranged in the control housing for controlling the electromotive adjustment device, the signal transmission paths are respectively short. In this case, the housing is to be provided with the respective openings for the light beams. Then, the light transmitter and the light receiver can also, in accordance with the present disclosure, be arranged in the region of the printed circuit board for controlling the electromotive adjustment device. The embodiment in accordance with the present disclosure is suitable, for example, if the furniture part to be adjusted is a table board which can be adjusted by a lifting column. However, if the furniture part or the table board is adjusted by several lifting columns, it is advantageous, in accordance with the present disclosure, when the light transmitter and the light receiver are installed in a separate housing or in a further separate housing, since in this case a deformation of the furniture part can exclusively be recognized between the columns. In another embodiment according to the present disclosure, in which the table board is adjusted by two lifting columns, the light transmitter and the light receiver are arranged in the region between the lifting columns or in the region adjacent to the lifting columns, with the light transmitter and the light receiver being arranged in or on the housing of the control of the electromotive adjustment device.
In the case of a table which includes two table boards which are arranged and connected at an angle with respect to each other or which includes an angular or an arc-shaped table board, there can, according to the present disclosure, be more than two lifting columns which are arranged at a distance from one another. A first arrangement of light transmitter and light receiver can be fastened, for example, in the control housing under the one table board, wherein a second arrangement of light transmitter and light receiver is fastened in a separate housing under the other table board and/or under another table board section, which are in connection via a connecting cable or wireless connection with the control unit in the control housing.
The light beams can, for example, be of known types such as coherent, polarizing, pulsating, visible, infrared and the like. Alternatively, in accordance with the present disclosure, the light waves can also be transmitted by optical waveguides.
The connections between the housing and the furniture part are spaced relatively far from one another. Thereby, the registration of the deformation will become especially precise.
It is within the scope of the present disclosure, that the respective angle enclosed by the two light beams, in relation to the surface of the furniture part to be adjusted they are facing, is a relatively small acute angle, so that the entire system can respond in an especially sensitive way. This angle could lie in the range of 35°, for example, and can, for example, lie in a range of 15° to 50°, according to other embodiments of the present disclosure.
It is advantageous, according to the present disclosure, if the signals generated by the light receiver can be converted into electrical signals by the signal converter, and if the signals can be supplied to the control electronics of the control unit.
It is provided in a further embodiment according to the present disclosure that the signals generated are filtered in such a way that the system will only respond if a specific continuity is given. That is, the system will not respond in the case of a sudden deformation caused by a respective action of force. Such an action of force would occur, for example, if an object is placed from a specific height without any restraint and thereby an initially pulse-like signal is converted in the signal chain by a series-connected filter into a filtered signal, which is then supplied to the control electronics of the control unit. The filtering of the signals is done by a generally known bandpass filter. Depending on the type of configuration of the filter, slow and/or rapid changes of the signal can be filtered out. The limiting frequency of the respective filter can be adjusted in a known manner and is adjusted to the adjustment speed of the piece of furniture. In the case of an adjustable piece of furniture with a relatively high adjustment speed, at least one filter is provided which has at least one relatively low limiting frequency.
In accordance with the present disclosure, the light beam is guided through light guide channels in order to prevent scattering of the light beams.
In accordance with the present disclosure, the light transmitter is a infrared diode and the light receiver is a infrared transistor.
In an embodiment of the present disclosure, the furniture part to be adjusted is a table board to be adjusted by at least one lifting column. Tables are also known which are designated as so-called angular combinations and are provided with two table boards. Two of the systems which were described above will then become necessary.
It is sufficient, according to the present disclosure, if one light receiver and one light transmitter are used for determining the deformation of the furniture part. However, it is also, within the scope of the present disclosure, that several light transmitters and light receivers are used.
In an embodiment according to the present disclosure, the generated light beam is directed directly against the furniture part or directly against the table board. In another embodiment according to the present disclosure, a further component is coupled with the furniture part which follows the movement and the deformation of the furniture part or the table board, wherein a glued on element, a sticker, a reflection film, a reflector or the like may be used as the further component.
Furthermore, in accordance with the present disclosure, an apparatus is further provided for adjusting the light intensity, which is at least connected to the light transmitter or to the control unit. The light intensity of the emitting light transmitter adjusts to the intensity of the light received. As a result, the safety device can advantageously be brought in connection with a plurality of surfaces which reflect with different intensities. If, for example, the safety device is brought in connection with a low-reflection surface, an electronic control and evaluation system, which is in connection with the light receiver, will recognize an averagely weak signal of the light receiver and will change the intensity of the light-transmitting signal until the signal has assumed a predetermined average value on the light receiver. This automatic change occurs very slowly from a time point of view. Notice must be taken in this connection that, for the recognition of a case of pinching, it is not the light intensity on the receiver that is relevant but its change, and especially its rapid and/or sudden or rapidly progressing change in form of the change velocity, which can be filtered out by the aforementioned filter from the signal curve of the light receiver.
As described above, the light transmitter and the light receiver are arranged in a housing. A support is provided in accordance with an advantageous embodiment of the present disclosure. That support can be designated as a kind of detector support and which can also be arranged, in an embodiment according to the present disclosure, as a housing. This concerns an element or a number of elements on which the light transmitter and/or the light receiver can be fixed or mounted. In an embodiment of the detector support according to the present disclosure, the detector support includes, two mirrored components with recesses in the shape of shells, which at least form the light guide channels and/or the receivers for the light transmitter and/or the light receiver. In accordance with an embodiment of the present disclosure, the detector support includes at least one body and can, for example, be sealed with a cover, in accordance with an embodiment of the present disclosure. The detector support can, advantageously, include the light guide channels and the receivers for the light transmitter and/or the light receiver in such a way that the light transmitter and/or the light receiver together with the detector support mounted in this way form a pre-mounted component. That is so that the light transmitter and the light receiver are aligned and arranged at a predetermined distance from one another. The detector unit thus formed can then be inserted and mounted into a housing in form of a control housing, a manual switch housing or a separate housing.
Other aspects of the present disclosure will become apparent from the following descriptions when considered in conjunction with the accompanying drawings.